A portable smart device (PSD) is a portable electronic device having a processing system and a housing, which is conveniently carried by a human being on their person. Examples include a cellular phone, a portable music player, a tablet computer, an e-reader, a portable computer, a smart watch, smart glasses, or other wearable smart device. Typically, a PSD will have means for information entry—a user interface (UI), which might include a display, e.g., a touch screen; a keyboard; tactile controls; a camera; a microphone; a sound system; or tactile output, such as vibration. A PSD may have access to a network (e.g., a local, wide area, and/or personal network) through one or more wireless interfaces, such as WiFi, cellular network, or BLUETOOTH®. The processing system may include a processor, and various forms of tangible nontransitory computer-accessible storage. The PSD may facilitate geolocation of the device by one or more technologies, such as GPS, beacons, or cell phone towers, alone or in combination. Such a PSD can be tracked geographically, with varying accuracy depending upon the location technology(ies) used.
Logic on a PSD with GPS can determine its location and how its location changes over time. An application running on the PSD can transmit its location to a remote system. Thus, so long as GPS is enabled, such a device can be tracked, often with 10 m horizontal resolution or better. GPS location is available in many places outdoors, but might not be available inside some buildings. Within a building, beacons or other technologies may be viable for tracking a PSD.
Some PSDs have multiple modes of location services, a high resolution (HIRES) mode and at least one low resolution (LORES) mode. A LORES mode provides less location accuracy than HIRES mode, but uses fewer or different resources of the PSD, and so consumes less electricity. Typically, electricity is provided to a PSD by a battery that must be recharged periodically. Useful battery life between charging events can be short. A software application running on the PSD can specify to the operating system when it requires HIRES mode and when LORES mode is adequate. When a LORES mode is adequate for one application, another application might still require the operating system to keep the PSD in HIRES mode. Thus, while HIRES tracking can be demanded by a PSD, transition from HIRES to LORES mode can merely be suggested. Access to these location tracking levels and functions may be provided to software executing on the PSD as services by its operating system.